Using a continuous rope or belt as a conveyor looped between a sheave at a particular destination and a sheave at a particular origin to move fluid is known in the prior art. Often the fluid conveyor is used to lift water or oil from beneath the surface of the ground to a storage receptacle on the surface. In this specific use of lifting fluid up to the surface, a well bore of sufficient length to reach the fluid is drilled and a fluid entraining conveyor or belt is secured around a sheave submerged in the fluid. A sheave system rigged on the surface is designed to minimize the effort required to lift the fluid entraining conveyor to the surface. The system must have sufficient traction between the sheaves and the conveyor to lift the combined weight of the conveyor and the fluid. Typical fluid conveyors of the prior art use a mechanical device to turn one sheave which pulls a rope up out of a well and returns the rope back into the well as it unwinds off the sheave. The fluid in the well follows the rope up and is subsequently collected in a containment vessel on the surface.
The efficiency of a fluid conveyor is determined by the amount of product collected as compared to the amount of energy used to run the device. Efficiency is lost when the conveyor slips on the drive sheave due to low traction between the conveyor and the sheave. Slippage causes wear on the conveyor and therefore reduces its useful life. To generate sufficient traction to prevent slippage, tension in the rope is typically high. The tension in the conveyor being a combination of factors such as, the type of fluid being lifted, the speed of the conveyor, the diameter of the conveyor, and the friction of the conveyor against the sheaves. A common problem with the fluid conveyors of the prior art is the failure of the conveyor due to slippage or high tension. The typical lifespan of the conveyor used in the prior art is approximately ninety (90) days. The relatively short lifespan of the conveyor increases the cost of the system which is a distinct disadvantage of the prior art.
Typical of the prior art is U.S. Pat. No. 4,652,372 to Threadgill. Threadgill discloses a liquid separator utilizing an endless belt for skimming extraction of oil from a liquid body and doctoring rollers for gathering the oil from both sides of the belt. The endless belt is fabricated from a material which is preferentially wettable by the liquid to be extracted. One drive roller winds the belt up out of the well and around a pair of doctoring rollers. Both sides of the belt engage a doctoring roller to skim the liquid off the belt. An additional roller positioned in the liquid maintains tension in the belt. The tension in the belt and the skimming process needed to remove the liquid from both sides of the belt tend to shorten the lifespan of the belt.
U.S. Pat. No. 6,158,515 to Greer, et al. discloses an artificial lifting device for well fluids using a continuous loop of fibrous material, such as a rope. The rope loop is formed around a drive sheave on the surface with a return sheave down inside of the well. The drive sheave has ridges along the side surfaces of a groove. The rope lays in the groove in contact with the ridges. A motor rotates the drive sheave, as guides and wipers direct the rope into the drive sheave and to the wipers. The wipers are slotted cards that scrape a quantity of fluid from the outside surface of the rope. The useful life of the rope is diminished by the contact with the ridges in the groove and the scraping of the wipers.
U.S. Pat. No. 5,080,781 to Evins, IV discloses a down-hole hydrocarbon collector that incorporates an endless absorption belt for collecting low-viscosity hydrocarbon liquids from a well and pumping those liquids to the surface. The collector of the invention has a means for driving the belt through a body of liquid to absorb low-viscosity hydrocarbons, which includes rollers engaging the endless belt in a manner that squeezes the hydrocarbons from the belt. The use of springs enables the squeezing of the belt between rollers. The squeezing of the belt exposes the belt to additional abrasion and hence limits its lifespan.
U.S. Pat. No. 5,423,415 to Williams discloses a rope pump for conveying fluid-like material from a reservoir to a select location. The surface assembly for the rope pump includes an endless rope, sheaves for forming the endless rope into a loop extending between the reservoir and the select location and a drive for driving the rope about the sheaves. The drive includes a first and second sheave each having a plurality of circumferential grooves. The endless rope is wrapped between the first and second sheaves in the grooves in a block and tackle fashion. A tensioning wheel biases the rope to maintain the rope in constant engagement with the final grooves of the first and second sheave. The tensioning wheel provides constant tension on the rope on the drive sheaves to continuously eliminate rope slack. The constant tension in the rope, especially on the downward side of the loop puts undue strain on the rope and reduces its lifespan.